Methods And Systems To Discriminate Betwen Psk And Fsk Signals

(19) United States

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US 20100316168Al

c12) Patent Application Publication
Ha et al.

(lO) Pub. No.: US 2010/0316168 Al
(43) Pub. Date: Dec. 16, 2010




(54) METHODS AND SYSTEMS TO DISCRIMINATE BETWEN PSKAND FSK



(51) Int. Cl.

Publication Classification

SIGNALS(76) Inventors: Stephen T. Ha, Greenville, TX (US); Michael L. Mahaffey, Austin, TX (US); FrankA. Boyle, Melissa, TX (US)


Correspondence Address:
O'KEEFE, EGAN, PETERMAN & ENDERS LLP
1101 CAPITAL OF TEXAS HIGHWAY SOUTH,
#C200
AUSTIN, TX 78746 (US) (21) Appl. No.: 12/456,075
(22) Filed: Jun.11,2009

H03D 3100 (2006.01)
H03D 1100 (2006.01)
(52) U.S. Cl.......................................... 375/322; 375/340 (57) ABSTRACT
Methods and systems are disclosed herein for discriminating phase-shift-key (PSK) modulated signals from frequency­ shift-key (FSK) modulated signals inreceived signa!streams. First, a bit frequency analysis is applied to a digital signa! stream representing the received signa!stream. The bit fre­ quency analysis computesbit frequencies for bit segments within the digital signa!stream. These bit frequencies are then summed in an array to form a bit frequency histogram. Sec­ ond, a bit phase analysis is applied to the digital signa!stream. The bit phase analysis computes bit phases for bit segments within the digital signa! stream. These bit phases are then summed in an array to form a bit phase histogram.Spikes within the bit frequency and bit phase histograms can be used to determine whetherthe received signa!stream includes FSK or PSK signals. An enhanced bit phase analysis can also used, ifneeded.






122



123




116

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PSK-BASED RECEIVER SYSTEM SYSTEM
140
124 120 142PSKIFSK EXTERNAL FSK-BASED DETECTION DEVICE
SYSTEM




































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112 ADDITIONAL 134

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DIGITAL DETECTION PROCESSING SIGNAL CIRCUITRY (OPTIONAL)
TRI= AM

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202 RECEIVE DIGITAL SIGNAL
STREAM




204 PERFORM BIT
FREQUENCY VES
ANALYSIS


No
206 PERFORM BIT
PHASE ANALYSIS



208




UTILIZE ENHANCED PHASE ANALYSIS
USING REPETITION
INTERNAL ANALYSIS


210


OUTPUT PSKIFSK DETERMINATION







FIG. 2


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Freq Sample in lncrement Steps of 39 kHz

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